1,720,965 research outputs found
Effects of climate changes on the Mediterranean nektonic communities, and consequences on commercial fisheries
No full textThe effects of Climate Change on the nektonic communities and fisheries of the Mediterranean Sea were studied based on the northern Adriatic case.
A characterisation of the vulnerability of the northern Adriatic ecosystem to climate change allowed to define its role as an early proxy to signal the effects of climate-driven modifications in the Mediterranean, due to its peculiarities that configure it as a boreal enclosure.
An analysis of landings both from the open sea and from the Venice Lagoon fisheries indicated a high potential vulnerability due to the catch being mainly composed of cold and temperate affinity species, which are negatively impacted by the climate regime modifications, while thermophilic invasive species are present but negligible.
Results from a food-web model showed that the area in the future may experience an impoverishment in biomass and diversity, and that management will need to confront with reduced resources, rather than with a different community composition.
Gli effetti dei cambiamenti climatici sulle comunità nectoniche e sulla pesca nel Mediterraneo sono state studiate basandosi sul caso nordadriatico.
L’indagine sulla vulnerabilità del sistema nordadriatico ai cambiamenti climatici ha permesso di definire il suo ruolo di early-proxy rispetto agli effetti dovuti al clima nel Mediterraneo, grazie alle peculiarità che lo configurano come enclosure boreale.
L’analisi dello sbarcato della pesca in mare e in Laguna di Venezia ha evidenziato un’alta vulnerabilità dovuta alla proporzione significativa nelle catture di specie ad affinità fredda e temperata, che sono negativamente influenzate dai cambiamenti nel regime termico, mentre le specie termofile sono presenti in quantità trascurabile.
I risultati di un modello di food-web hanno mostrato che nel futuro l’area potrebbe subire una riduzione di biomassa e diversità, e che la gestione dovrà confrontarsi con una riduzione delle risorse, piuttosto che con una diversa composizione della comunità
Vulnerability of the Northern Adriatic Sea Fishery to Climate Change
No full textWithin the context of marine environments, nekton assemblages are recognised to provide several kinds of ecosystem services, both fundamental and demand–derived. They contribute, indeed, to enhance the biodiversity, the ecological processes and
finally the system resilience. They also directly support the production of goods, such as in the case of renewable resources exploited by commercial fisheries. The problem of the impacts of climate change on this component of marine ecosystems,
with the related consequences on ecosystem services, becomes therefore an interesting issue. In this context, the northern Adriatic Sea, hosting several species adapted to boreal climatic conditions, can be considered a good case study. By
analysing the composition of landings from fisheries in terms of thermal affinity groups, we highlighted the potential vulnerability of these activities. Catches, indeed, were shown to be mainly composed of cold and temperate affinity species, whereas
the contribution of warm ones resulted very low. Given the significant negative relationships between the cold and temperate groups with the recorded variations of the thermal regime and the latest projections by the IPCC in terms of ocean temperature raise, fishing activities, both professional and recreational, can be expected to experience severe consequences
Modeling species invasions using thermal and trophic niche dynamics under climate change
Full text linkChanging marine temperatures modify the distributional ranges of natural populations, but the success of invasion of new areas depends on local physical and ecological conditions. We explore the invasion by thermophilic species and their ecosystem effects by simulating a sea surface temperature increase using a trophodynamic model for the northern Adriatic Sea (NAS), in which thermal and trophic niches are explicitly represented for each thermophilic non-indigenous species and native species. The NAS acts as a cul-de-sac for local species, preventing a further poleward migration as a response to temperature rise. In this situation, model results showed that effects of warming and invasion produced complex, non-linear changes on biomasses but never resulted in a complete overturn of a group of native species and/or a bloom of invasive ones. Despite this, the diversity index stabilizes at increased values after simulating invasion, possibly indicating that in such enclosed systems the establishment of invasive species could represent enrichment in ecosystem structure. In addition, the absence of complete species substitution clearly showed the contribution of resident species towards increasing the resilience, i.e. the capability of the system to cope with invasion without changing substantially. Contrasting scenarios highlighted that changes in ecosystem primary production and species adaptation had secondary effects in ecosystem structure, while results for scenarios with different exploitation levels indicated that fishing can destabilize community structure in these change contexts, e.g. reducing community resilience. The results confirmed the importance of an ecological niche approach to analyze possible effects of invasion and highlighted the complexity of dynamics linked to temperature-driven species invasion’, in terms of both the predicted strength of impacts and the direction of biomass change
Specie aliene termofile e funzionamento dell’ecosistema: il caso di studio dell’Alto Adriatico
No full textInside and outside the boundaries: contribution of the valli da pesca to the Venice lagoon Ecosystem Services
No full textThe Venice lagoon is a social-ecological system, result of centuries of co-evolution between natural and anthropogenic drivers. All this produced a complex interacting set of different habitats and parts, including
some confined, man-managed areas known as valli da pesca. These areas, similar to ‘miniature lagoons’, have progressively been separated in a permanent way from the lagoon itself, depending almost completely on human intervention for functioning and maintenance. Due to both the “artificial” origin and
difficulties of accessing, these portions of the lagoon have previously been excluded from analyses, surveys, monitoring programs. The present work constitutes the first attempt of a spatially explicit Ecosystem Services (ESs) assessment of the entire lagoon, included the valli da pesca, both in terms of capacity and flow. Obtained results showed that these areas, despite they represent just the 18% of the total lagoon area, play an important ecological role, contributing for 35% of the ESs capacity and 27% of the flow in comparison with the whole lagoon. Furthermore, the valli da pesca showed that different management strategies, aimed to maximize just a single ES, like aquaculture or hunting (or both), could have significant contrasting effects on the landscape features
Permanent trawl fishery closures in the Mediterranean Sea: An effective management strategy?
Full text linkSince June 2010 the Italian government prohibited the trawling activity within three nautical miles from the coast or within the 50 m isobath. This decision was expected to have a great impact on trawl fishing activities, but at the moment no real assessment of the effects on catches and possible ecological implications has been undertaken. In order to fill this gap, an assessment on the North Western Adriatic Sea coast has been performed. Landings per Unit of Effort (kilograms per boat per day) for each trawling fleet segment have been analysed, by comparing on a monthly basis the before (2007-2009) and after ban (2011-2013) period. The comparison was carried out considering total landings and the six main species targeted inside the three miles area (sand smelt, cuttlefish, red mullet, sole, turbot, and mantis shrimp). Within a general reduction of total landings, a differential effect based on the analysed metiers was detected, with small trawlers being more negatively affected than the large and rapido ones, which showed, for some species, positive impacts. From an ecological point of view, though, no positive overall effects were detected, probably due to the fact that the adopted measure is not sufficient to reduce the overexploitation. In any case, all this is affecting the structure of the small-scale fishery in the area, since small trawlers are changing métier, moving towards the artisanal fishery, with deep impacts on the very coastal area that the trawling ban was designated to protect, compromising all possible benefit
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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